This is the 7492nd most frequent Japanese word.
免税
Tax-free.
The term "免税" (duty-free) is used here as an adjective modifying the noun "店" (shop) to describe shops exempt from tax.
この空港には免税店があります。
This airport has duty-free shops.
Here, "免税" is used as a noun referring to the concept or policy of tax exemption received by eligible individuals.
外国人観光客は一定の条件下で免税を受けられます。
Foreign tourists can receive tax exemption under certain conditions.
"免税" (tax exemption) in this sentence is part of the compound noun "免税制度" (tax exemption system), referring to a structured tax-free policy.